**3. Banana phytochemicals and bioactives**

*Banana Nutrition - Function and Processing Kinetics*

(DW/FW?) for 'Dwarf Brazilian' banana cultivar.

accumulate β-carotene of about 2230 mg/100 g [39].

Dessert and cooking banana contain different forms of vitamins in varying concentrations among the known cultivars worldwide. According to the reports of USDA [23] and Wills et al. [34], the vitamin C levels for 'Cavendish' banana estimated using high-performance liquid chromatography (HPLC), ranged from 2.1 to 18.7 mg/100 g (DW/FW), which however, varies considerably among different cultivars. The average vitamin C (**Table 2**) content for 'Dwarf Brazilian' (*Musa* AAB 'Santa Catarina Prata') was found to be 12.7 mg/100 g and 4.5 mg/100 g for 'Williams' [13]. These results agree with the report of Wenkam [35], who reported vitamin C values of 5.1 mg/100 g (DW/FW?) for 'Williams' and 14.6 mg/100 g

Dessert banana contains substantial levels of provitamin A carotenoids (PVAC), but few cultivars with orange- or yellow-coloured pulp are known to have higher concentration of carotenoids [15]. Vitamin A deficiency has been reported to be a public health concern identified in almost 118 countries in the world, with highest prevalence in Asia and Africa, as their diets are mainly cereals and tubers [1]. Researchers from Australia (Queensland University of Technology) have concocted Cavendish banana with high amounts of β-carotene, a precursor of vitamin A. The carotenoids mostly found in fully developed bananas are lutein, α- and β-carotene. The fruit pulp is also rich in carotenoids, while the peel contains low amounts [36]. It is reported that during ripening the amount of carotenoids increase [20, 34]. Similar observation was reported by Kanazawa and Sakakibara [37], which contradicts the report of Gross and Flugel [38] who found carotenoid content decreasing during initial stage of ripening. As can thus be seen, different cultivars of *Musa* spp. contain different amounts of carotenoids. Banana and plantain fruits with orange flesh are rich in VAC [38, 39]. One variety of banana, 'Karat' of Micronesia, was reported to

Banana and plantain are very rich in K, an essential element for maintaining human blood pressure and for proper functioning of the heart [40]. The fruit is also rich in Mg, Fe, Cu and Mn [20]. In the works of Pareek [10], the average K content for Hawaii's bananas ('Dwarf Brazilian' and 'Williams') were reported to be 330.6 mg/100 g (FW). Similarly, it was reported that fruits cultivated in Tenerife, were observed to contain a K content of 5.09 mg/g (FW), P content of 0.59 mg/g (FW), Ca content of 0.38 mg/g (FW) and Mg content of 0.38 mg/g (FW) [10, 41], though it was reported by the authors that the area of origin had a major effect on the occurrence of the minerals. Varietal differences had no effect on concentration of minerals present except for Fe. In the works of Forster et al. [42], differences were observed in the mineral content of bananas grown in both Ecuador and Tenerife. High Na, K, Mg and Fe contents were found for bananas grown in Tenerife, while high Ca, Cu, Zn and Mn contents were reported for bananas grown in Ecuador. This difference was attributed to agricultural practices, geographical location and soil composition [42]. Mineral composition of banana samples according to degree of ripeness was reported for the fruits obtained from Nigeria: 73.47% ash, 0.68% Zn, 0.146% Mn for unripe samples; 77.19% ash, 0.80% Zn, 0.271% Mn for ripe samples and 79.22% ash, 0.78% Zn for overripe samples [43]. Similarly, the peel of banana cultivars obtained from Cameroon contained relatively high minerals: K (50.0 mg/g DW), P (22.2 mg/g DW), Mg (11 mg/g DW) and Ca (18 mg/g DW) [44]. Generally, bananas contain low amounts of Ca, however, Micronesian

**2.3 Vitamins**

**2.4 Minerals**

**32**

cv. 'Krat' is relatively high in Ca [39].

Phytochemicals have been reported to be an immense source of anticancer medications and chemopreventive agents [45]. These plant chemicals exert some of their actions through interactions with essential enzymes that regulate the activities in genes. Banana contains various bioactive compounds such as phenolics, carotenoids, alkaloids, glycosides, phlobatannins, tannins, terpenoids, saponins, steroids, biogenic amines and phytosterols, which are highly desirable in diet as they exert health beneficial effects [11, 32, 46]. These composites are helpful in protecting the body against oxidative stress due to their antioxidative activities [47], controlling gene expression in cell proliferation and apoptosis and important in controlling blood pressure [48]. The incorporation of banana pulp and peel in various food products could add value since they have health benefits [47]. Thus, banana pulp and peel can be used as natural sources of antioxidants and provitamin A. Banana peel is reported to have higher antioxidant capacity than banana pulp [49–53]. Furthermore, phenolic content of banana peel was higher compared to other fruits such as avocado, pineapple, papaya, passion fruit, water melon and melon [50]. However, it is recommended that to effectively recover and utilise phenolic compounds from banana peels, it is important to evaluate its chemical profile, factors affecting the levels of phenolic compounds in the peels such as antinutrients, and potential use of these compounds as food ingredients or nutraceuticals. It is important to understand how these bioactive compounds found in fruits and vegetables limit or prevent oxidative stresses as a free-radical scavengers or metalchelating agents. In the report of Liu [53], it was emphasised that there has to be a balance between oxidants and antioxidants for normal functioning of the body cell and/or sustaining optimal physical condition in the human body. Too much oxidants in the human body result in damage to the biomolecules such as proteins, lipids carbohydrates and DNA. Hence, to understand the mechanism of action of antioxidant, it is imperative to understand the formation of free radicals and their ability to damage macromolecules and nucleic chains.

Phenolic compounds have been implicated to be present in banana fruits. Although, banana peels contain more tannin compared with its pulp, tannins in the fruit confer an unpleasant astringent taste on the fruit. The astringency in ripe fruit is reduced, which is associated with a change in the structure of the tannins, rather than a reduction in their levels, as they form polymers [28]. When banana fruit is cut, oxidative browning occurs due to the presence of polyphenols. Report of different studies has shown that banana peels of different cultivars contain varying concentrations of total phenolic compounds (TPC). In the works of Nguyen et al. [54], it was reported that total phenolics, flavonoids and antioxidant activity of banana pulp and peel flours, Cv. 'Kulai Hom Thong' was shown to contain 3.0 mg of gallic acid equivalent (GAE)/gFW, while 'Kulai Khai' was reported to contain 0.9 mg of (GAE)/ gFW. Similarly, banana cv. 'Pisangmas' from Malaysia was reported to contain TPC ranging from 0.24 to 0.72 mg GAE/g FW, depending on the extraction method [32]. Sulaiman et al. [52], also reported significant differences in the antioxidant activity, total phenolic and mineral contents of eight Malaysian banana cultivars. Flavonoids epicatechin and myricetin 3-O-rhamnosyl-glucoside were identified in flour of organic acid pretreated "Mabonde", "Luvhele" and "M-red" cultivars at different concentrations [55]. Authors Bennett et al. [56] and Borges et al. [57] also reported the presence of catechin and gallic acid in pulp and peel of ripe and unripe banana cultivars. Similarly, plantain a banana cultivar belonging to the AAB, ABB or BBB group [58] have also been reported to contain high concentration of hydroxycinnamic acids (ferulic acid–hexoside with 4.4–85.1 μg/g DW) in its pulp [32]. Plantain peels are rich in flavonol glycosides and rutin ranging from 242.2 to 618.7 μg/g DW.

Polyphenols are extremely diverse group of secondary metabolites, having sweetsmelling ring with one or more hydroxyl groups. Polyphenols have large range of structures and functions and can be classified as subgroups of flavonoids, phenolic acids, tannins, stilbenes and coumarins. These secondary metabolites are very essential in the metabolism, reproduction and growth of plants. Polyphenols also protect plants against pathological parasites, predators, fungal infections and viruses [53].

#### **3.1 Banana volatiles**

Tropical flavours including coconut, mango, mandarin as well as the combination of fruit and vegetable flavours are gaining popularity, with the African marula fruit and mangosteen being strong super fruit contenders [59]. Banana fruit flavour has been attributed to the presence of esters with inherent alcohols which contribute to flavour enhancement [60]. Alcohols and insignificant carbonyl composites present in banana are called green and woody notes [61], while the ester fraction contributes to fruity notes [62–64]. The presence of esters cause the sweet-smelling profile in ripe bananas, while that of unripe banana is determined by the presence of pentyl and hexyl alcohols, aldehydes and ketones [65]. Components of the fruity notes present in banana fruit includes 3-methylbutyl acetate, isoamyl butanoate and isoamyl isovalerate [66–68]. Esters constitute a major fraction of emitted volatiles from fresh banana fruits [64]. Esters can also be used to differentiate cooking bananas from desert bananas; in that cooking bananas lack esters, whereas the same form a major component of flavour present in desert bananas [69].

Aroma in banana fruit is characterised by the presence of various volatile compounds varying in concentration among cultivars [70, 71]. Pino [72] reported the presence of 250 volatiles in fresh and processed banana products, though few of these volatiles have been isolated as flavour contributors. Essential components affecting taste of banana fruit includes d-glucose, d-fructose and sucrose for sweetness, while citric, l-malic, oxalic and succinic acids have been implicated for sourness [65, 73]. Determination of volatiles that has unique character of the fruit is important as it produces the principal characteristic flavour of the fruit [74, 75]. The most appealing property of banana required by most consumers apart from their nutritional and health benefits is the flavour [76, 77].

#### **3.2 Nutrigenomics of banana nutrients**

With the ever changing nutrition-related health problems in developing economies, there is a gradual shift in nutrition research that focuses on how nutrition can be maximised in maintaining homeostasis at the cellular, tissue, organ and system level of the body [75]. This, however, requires the understanding of nutrient interactions at the molecular level. Nutrigenomics is the research into nutritional genomics, which also include nutrigenetics. In the works of Neeha and Kinth [78], nutrigenomics is defined as the study of the interaction between nutrients and genes, proteins and metabolic processes such as DNA and RNA synthesis and glycogenesis. Nutrigenomics focuses on the effects of nutrients on genome, proteome and metabolome as well as the interactions among these nutrients and nutrient-regimes in the body [78]. Through the application of molecular biology and genomic tools, researchers have identified genes responsible for the production of nutritionally significant proteins such as digestive enzymes, transport molecules and cofactors at their site of use [79]. Studies on genetic improvement of banana fruit is advancing at a rapid pace, using modern biotechnology which includes genetic engineering. Other programmes such as the use of banana as edible

**35**

*Banana Bioactives: Absorption, Utilisation and Health Benefits*

vaccine delivery system and biofortification of bananas to increase their β-carotene, α-tocopherol and iron contents are on the way [79]. These improvements will be most beneficial for regions of the world that consume bananas as their major staple. However, genetic improvement of banana fruit is a major challenge as cultivated banana fruits are basically sterile or possess low fertility with conventional breeding, though possible in delivering a few acceptable cultivars [79]. In the WHO [80] guideline on vitamin A supplementation in infants and children 6–59 months of age, about 19 million pregnant women and 190 million preschool age children from parts of Africa and South-East Asia were reported to be affected by vitamin A deficiency (VAD). Similarly, VAD is reported to be responsible for about 6% of child mortality below the age of five in Africa and 8% in South-East Asia [79]. Some banana cultivars have been implicated for the presence of dietary provitamin A carotenoid (PVAC) due to their characteristic orange-coloured fruit flesh. Carotenoid composition of the PVAC implicated banana cultivars has shown the presence of *trans-*α-, *trans-*β-, *cis-*β-carotene and lutein [21]. These notable differences in PVAC composition of the fruit could have significant consequences on the nutritional profile of banana varieties [79]. Banana bioactive compounds have potential for preventing various diseases when used as an ingredient in the food

**4. Utilisation of banana bioactives as nutraceuticals and food** 

According to the Science Forum, nutraceuticals is defined as a "diet supplement that delivers a concentrated form of a biologically active component of food in a non-food matrix to enhance health" [83]. Anyasi et al. [58] in their study further added that nutraceutical can also be extracted from a different product derived from the food and pharmaceutical industry, herbal and dietary supplement market, and the pharmaceutical/agribusiness and nutrition conglomerates. Raw banana shows higher amount of functional ingredients such as dietary fibre, resistant starch and total starch, which allows banana to impart health benefits to humans when incorporated in food products [84]. **Table 3** highlighted the effects of banana bioactive compounds as a value-added ingredient in food processing. It is important to understand fruit maturity during preparation of banana flour to produce desirable food products. Ripe banana can be considered for industrial processing, which could result to products that are comparable to those obtained from apple, juice, fruit drinks, fermented drinks, stewed fruit, puree, marmalade, jam, flakes, confectionery, pastry, sorbets and ice-cream. Raw bananas can be considered as a source for new food innovation and development for partial or preprocessed food products like snacks and breakfast cereals [82]. Mixed pulp and peel flour from green banana has higher ash, total fibre and total phenolics than traditional wheat flour [85]. The addition of banana flour increases the indigestible fraction and the content of phenolic compounds in spaghetti [86]. Crackers containing greater amount of green banana flour showed increased antioxidant capacity [87]. The influence of green banana flour as a substitution for cassava starch on the nutrition, colour, texture and sensory qualities of snacks was reported for raw banana flour [87]. In the study, increased nutritional value including dietary fibre, polyphenol content and antioxidant capacity of the snacks was noted. Unripe banana peel can be incorporated in a sponge cake without imparting negative effects on the sensory quality [88]. The application of banana by-products, an underutilised renewable food biomass with potential in food and nutraceutical industry as a means of promoting green

*DOI: http://dx.doi.org/10.5772/intechopen.83369*

industry [81, 82].

**ingredients**

*Banana Bioactives: Absorption, Utilisation and Health Benefits DOI: http://dx.doi.org/10.5772/intechopen.83369*

*Banana Nutrition - Function and Processing Kinetics*

**3.1 Banana volatiles**

Polyphenols are extremely diverse group of secondary metabolites, having sweetsmelling ring with one or more hydroxyl groups. Polyphenols have large range of structures and functions and can be classified as subgroups of flavonoids, phenolic acids, tannins, stilbenes and coumarins. These secondary metabolites are very essential in the metabolism, reproduction and growth of plants. Polyphenols also protect plants against pathological parasites, predators, fungal infections and viruses [53].

Tropical flavours including coconut, mango, mandarin as well as the combination of fruit and vegetable flavours are gaining popularity, with the African marula fruit and mangosteen being strong super fruit contenders [59]. Banana fruit flavour has been attributed to the presence of esters with inherent alcohols which contribute to flavour enhancement [60]. Alcohols and insignificant carbonyl composites present in banana are called green and woody notes [61], while the ester fraction contributes to fruity notes [62–64]. The presence of esters cause the sweet-smelling profile in ripe bananas, while that of unripe banana is determined by the presence of pentyl and hexyl alcohols, aldehydes and ketones [65]. Components of the fruity notes present in banana fruit includes 3-methylbutyl acetate, isoamyl butanoate and isoamyl isovalerate [66–68]. Esters constitute a major fraction of emitted volatiles from fresh banana fruits [64]. Esters can also be used to differentiate cooking bananas from desert bananas; in that cooking bananas lack esters, whereas the same

form a major component of flavour present in desert bananas [69].

nutritional and health benefits is the flavour [76, 77].

**3.2 Nutrigenomics of banana nutrients**

Aroma in banana fruit is characterised by the presence of various volatile compounds varying in concentration among cultivars [70, 71]. Pino [72] reported the presence of 250 volatiles in fresh and processed banana products, though few of these volatiles have been isolated as flavour contributors. Essential components affecting taste of banana fruit includes d-glucose, d-fructose and sucrose for sweetness, while citric, l-malic, oxalic and succinic acids have been implicated for sourness [65, 73]. Determination of volatiles that has unique character of the fruit is important as it produces the principal characteristic flavour of the fruit [74, 75]. The most appealing property of banana required by most consumers apart from their

With the ever changing nutrition-related health problems in developing economies, there is a gradual shift in nutrition research that focuses on how nutrition can be maximised in maintaining homeostasis at the cellular, tissue, organ and system level of the body [75]. This, however, requires the understanding of nutrient interactions at the molecular level. Nutrigenomics is the research into nutritional genomics, which also include nutrigenetics. In the works of Neeha and Kinth [78], nutrigenomics is defined as the study of the interaction between nutrients and genes, proteins and metabolic processes such as DNA and RNA synthesis and glycogenesis. Nutrigenomics focuses on the effects of nutrients on genome, proteome and metabolome as well as the interactions among these nutrients and nutrient-regimes in the body [78]. Through the application of molecular biology and genomic tools, researchers have identified genes responsible for the production of nutritionally significant proteins such as digestive enzymes, transport molecules and cofactors at their site of use [79]. Studies on genetic improvement of banana fruit is advancing at a rapid pace, using modern biotechnology which includes genetic engineering. Other programmes such as the use of banana as edible

**34**

vaccine delivery system and biofortification of bananas to increase their β-carotene, α-tocopherol and iron contents are on the way [79]. These improvements will be most beneficial for regions of the world that consume bananas as their major staple. However, genetic improvement of banana fruit is a major challenge as cultivated banana fruits are basically sterile or possess low fertility with conventional breeding, though possible in delivering a few acceptable cultivars [79]. In the WHO [80] guideline on vitamin A supplementation in infants and children 6–59 months of age, about 19 million pregnant women and 190 million preschool age children from parts of Africa and South-East Asia were reported to be affected by vitamin A deficiency (VAD). Similarly, VAD is reported to be responsible for about 6% of child mortality below the age of five in Africa and 8% in South-East Asia [79]. Some banana cultivars have been implicated for the presence of dietary provitamin A carotenoid (PVAC) due to their characteristic orange-coloured fruit flesh. Carotenoid composition of the PVAC implicated banana cultivars has shown the presence of *trans-*α-, *trans-*β-, *cis-*β-carotene and lutein [21]. These notable differences in PVAC composition of the fruit could have significant consequences on the nutritional profile of banana varieties [79]. Banana bioactive compounds have potential for preventing various diseases when used as an ingredient in the food industry [81, 82].
